A driver is travelling at high speed along a dry road when they suddenly notice a hazard ahead. State two factors, other than speed, that affect the thinking distance, and for each factor explain how it increases the thinking distance.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Thinking distance and braking distance together make up the stopping distance of a vehicle.
Model answer (4 marks)
1. Alcohol
Alcohol impairs the driver’s concentration and slows the time taken to recognise the hazard, so the reaction time is longer and the vehicle travels a greater distance before braking.
2. Tiredness
When the driver is tired, their alertness is reduced and it takes longer to react to the hazard, increasing the reaction time and therefore the thinking distance.
Alcohol impairs the driver’s concentration and slows the time taken to recognise the hazard, so the reaction time is longer and the vehicle travels a greater distance before braking.
2. Tiredness
When the driver is tired, their alertness is reduced and it takes longer to react to the hazard, increasing the reaction time and therefore the thinking distance.
Examiner tips
- Use the exact wording ‘reaction time’ – examiners look for this phrase.
- Show the causal link: factor → longer reaction time → longer distance travelled before braking.
- Mention that the factor must be different from the first one.
- Keep each point concise – 2 marks each.
Common mistakes
- Using a factor that is the same as the first (e.g. both alcohol and distraction).
- Failing to explain that the factor increases reaction time.
- Using vague terms like ‘slower’ without linking to reaction time.
Mark scheme (4 marks)
- First valid factor that increases thinking distance (e.g. alcohol / tiredness / distraction / drugs)
- Explanation of how first factor increases thinking distance — it increases the driver's reaction time, so the vehicle travels further before the brakes are applied
- Second valid factor that increases thinking distance (must be different from the first, e.g. distraction / tiredness / alcohol / drugs)
- Explanation of how second factor increases thinking distance — it increases the driver's reaction time, so the vehicle travels further before the brakes are applied
Key terms in this question
Related
- All Pearson Edexcel International GCSE Physics (4PH1) revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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